<p>
    Implement a program that computes the sum of a 3D subarray of 32-bit integers.
    You are given an input 3D array <code>input</code> of length <code>N x M x K</code>, and two depth indices <code>S_DEP</code> and <code>E_DEP</code> and two row indices <code>S_ROW</code> and <code>E_ROW</code> and two column indices <code>S_COL</code> and <code>E_COL</code>.
    <code>S_DEP</code>, <code>E_DEP</code>, <code>S_ROW</code>, <code>E_ROW</code>, <code>S_COL</code> and <code>E_COL</code> are inclusive, 0-based start and end indices — compute the sum of <code>input[S_DEP..E_DEP][S_ROW..E_ROW][S_COL..E_COL]</code>.
</p>

<h2>Implementation Requirements</h2>
<ul>
    <li>Use only native features (external libraries are not permitted)</li>
    <li>The <code>solve</code> function signature must remain unchanged</li>
    <li>The final result must be stored in the <code>output</code> variable</li>
</ul>

<h2>Example 1:</h2>
<pre>
Input:  input = [[[1, 2, 3],
                  [4, 5, 1]],
                 [[1, 1, 1],
                  [2, 2, 2]]]
        N = 2, M = 2, K = 3
        S_DEP = 0, E_DEP = 1, S_ROW = 0, E_ROW = 0, S_COL = 1, E_COL = 2
Output: output = 7
</pre>

<h2>Example 2:</h2>
<pre>
Input:  input = [[[5, 10],
                  [5, 2],
                  [2, 2]]]
        N = 1, M = 3, K = 2 
        S_DEP = 0, E_DEP = 0, S_ROW = 0, E_ROW = 2, S_COL = 1, E_COL = 1
Output: output = 14
</pre>

<h2>Constraints</h2>
<ul>
    <li>1 &le; <code>N, M, K</code> &le; 500</li>
    <li>1 &le; <code>input[i]</code> &le; 10</li>
    <li>0 &le; <code>S_DEP</code> &le; <code>E_DEP</code> &le; <code>N - 1</code></li>
    <li>0 &le; <code>S_ROW</code> &le; <code>E_ROW</code> &le; <code>M - 1</code></li>
    <li>0 &le; <code>S_COL</code> &le; <code>E_COL</code> &le; <code>K - 1</code></li>
</ul>